Field of the Invention
Embodiments of invention relate to an organic light emitting display device and a method of manufacturing the same, and, in particular, to an organic light emitting display device and a method of manufacturing the same in which organic and inorganic thin films are formed on a polarization plate, and the polarization plate is attached to an organic light emitting panel so that the organic and inorganic thin films seal the organic light emitting panel, thereby achieving improved polarization and a simple sealing structure.
Discussion of the Related Art
An image display device to visually provide a variety of information increasingly becomes a core technology in communication and thus has been developed to be thinner and more lightweight to achieve improved portability while maintaining high performance. As a flexible display device bendable for effective space utilization and convenience is increasingly demanded, organic light emitting display devices are receiving much attention recently.
An organic light emitting display device may include an organic light emitting element array, each organic light emitting element of the array including an anode, an organic light emitting layer and a cathode disposed in this order on a substrate, and a capping layer to cap the organic light emitting element array.
The organic light emitting element operates as follows. When an electric field is applied between the anode and cathode respectively formed on both of opposite surfaces of the organic light emitting layer, holes and electrons are injected into the organic light emitting layer, and then are combined with each other, thus generating light emission. That is, in the organic light emitting layer, when the holes and electrons are combined with each other, an energy state thereof changes from an excitation state to a lower state, resulting in light emission.
The organic light emitting display device may advantageously be provided in a thin film form. However, the organic light emitting display device may suffer from not only deterioration caused by intrinsic factors, such as deterioration of the electrodes and light emitting layer due to oxygen and deterioration due to a reaction between the light emitting layer and an interface, but also deterioration caused by extrinsic factors such as effect of moisture, oxygen, or ultra-violet light, etc. For this reason, as to the organic light emitting display device, a packaging and/or encapsulation process may be important.
As to the organic light emitting display device, the encapsulation process may include a sealing process to dispose a cover substrate over a substrate having an organic light emitting layer formed thereon and provide a sealant at a peripheral inner surface of the cover substrate. Alternatively, the encapsulation process may include a sealing process to form alternate organic and inorganic thin films on a substrate having an organic light emitting layer formed thereon.
Now, a conventional encapsulation process will be described with reference to FIG. 1.
FIG. 1 is a cross-sectional view of an organic light emitting display device of a related art.
As shown in FIG. 1, a thin film transistor array 20 is disposed on a glass substrate 10, an organic light emitting element array 30 is disposed on the thin film transistor array 20, and an opposing glass substrate 40 is disposed on the organic light emitting element array 30.
A sealant is formed at a peripheral inner surface of the glass substrate or the opposing glass substrate 40 to seal the thin film transistor array 20 and the organic light emitting element array 30. Thus, the thin film transistor array 20 and the organic light emitting element array 30 may be protected from moisture and/or impact.
Further, a polarization plate 50 may be disposed over the opposing glass substrate 40 with an adhesive layer interposed therebetween, to prevent ambient or external light incident upon the organic light emitting display device from being reflected therefrom.
The organic light emitting display device may have the following problem.
The method of sealing the thin film transistor array 20 and the organic light emitting element array 30 using the opposing glass substrate 40 and the sealant may not be applied to on-demand flexible display devices because the opposing glass substrate 40 may not be bendable due to thickness thereof.
Therefore, as to the organic light emitting display device, the latter encapsulation process, that is, the sealing process to form alternate organic and inorganic thin films on a substrate having an organic light emitting layer formed thereon has been employed.
However, as to the latter encapsulation process, in addition to the alternate organic and inorganic thin films, a plastic film is required as a base substrate. The plastic film optically has an anisotropic property whereas the glass substrate optically has an isotropic property. Therefore, when external light is incident upon the organic light emitting display device, polarization may not operate as appropriate and thus external light may be reflected from the organic light emitting display device, so that external light is disadvantageously visible to a viewer of the organic light emitting display device. Further, since phase of light has been changed due to the thin films such as the plastic film added in the sealing process, arrangement of the thin films is required in consideration of the phase of light.